about the text box?

how can i make a new line in the text box without useing the ENTER (By code).This because i have 4 text boxes , i want to write in three and on lost foucs of the last one i mant these texts transfeired to the fourth text box. and if i repeart this o want the new line wich i wrote in the tree boxes come in a new line in the the fourthe text box ........ please i want the answer as sooooon as posible .